fix(stats): robust trade volume instead of a sybil-inflatable sum

The marketplace 'Sats Traded' was a naive sum of the self-reported amount tag on
31871, which two colluding accounts could inflate for free. tradedSats is now the
robust figure - mutual trades only (a listing attested by >=2 distinct pubkeys),
per-pair cap 3, amounts >1 BTC dropped - with tradedCount + tradedTraders, and
tradedSatsClaimed keeps the raw claim so the card shows both. Added query fields
=> PERSIST_BUSTER v5. No trade attestations exist on the relay yet (honest 0).

AGENTS.md

@@ -919,6 +919,16 @@ session with **no other memory of this project**. So:
     legitimate): **untagged pins** (the map draws them, the region rows only count
     tagged ones) and **auto-hidden** spots (the map drops them at `MapPage:847`;
     the stats can't know about reports without querying them).
+- **Anti-fake-volume on `/stats` (2026-10-01):** the marketplace "Sats Traded"
+  used to be a naive sum of the self-reported `amount` tag on `31871`, so two
+  colluding accounts could inflate it for free. `useGrowthStats` now computes
+  **`tradedSats` robustly** — **mutual trades only** (a listing attested by ≥2
+  distinct pubkeys), per-pair cap **3**, amounts **>1 BTC dropped** as junk —
+  plus `tradedCount` (mutual trades) + `tradedTraders` (distinct people), and
+  keeps `tradedSatsClaimed` (the raw claim) so the card shows both. New query
+  fields ⇒ `PERSIST_BUSTER` → **v5**. **There are no trade attestations on the
+  relay yet**, so the honest values are 0 today. (Broader anti-sybil plan —
+  claimed-vs-verified tiers, ring detection, PoW — is a follow-up.)
 - **Reverse geocoding hits Nominatim — disclosed (2026-10-01).**
   `src/lib/geocodeRegions.ts` (`reverseGeocodeRegions` / `geocodeBigDataCloud` /
   `pushRegionTags`) is the **single source of truth**, used by **spot create, spot

src/hooks/useGrowthStats.ts

@@ -98,8 +98,14 @@ export interface GrowthStats {
   totalListings: number;
   /** Completed trades (sale/purchase attestations; revoked excluded). */
   totalTrades: number;
-  /** Sats recorded across those attestations (self-reported). */
+  /** Robust sats: MUTUAL trades only, per-pair capped, junk amounts dropped. */
   tradedSats: number;
+  /** Raw self-reported sats across ALL attestations (a claim — sybil-inflatable). */
+  tradedSatsClaimed: number;
+  /** Mutual trades counted for the robust figure. */
+  tradedCount: number;
+  /** Distinct people involved in those mutual trades. */
+  tradedTraders: number;
   /** Trades by self-reported method (cash / lightning / trade / other). */
   tradesByMethod: { method: string; count: number }[];
 
@@ -278,11 +284,14 @@ export function useGrowthStats() {
       const trades = dedup(tradeEvents).filter(
         (e) => e.tags.find((t) => t[0] === 's')?.[1] !== 'revoked',
       );
-      let tradedSats = 0;
+
+      // Raw self-reported total — what the tags CLAIM. A sybil pair can inflate
+      // this without bound, so it is shown as "claimed", never the headline.
+      let tradedSatsClaimed = 0;
       const methodCounts = new Map<string, number>();
       for (const t of trades) {
         const amount = Number(t.tags.find((x) => x[0] === 'amount')?.[1] ?? 0);
-        if (Number.isFinite(amount) && amount > 0) tradedSats += amount;
+        if (Number.isFinite(amount) && amount > 0) tradedSatsClaimed += amount;
         const method = t.tags.find((x) => x[0] === 'method')?.[1] ?? 'other';
         methodCounts.set(method, (methodCounts.get(method) ?? 0) + 1);
       }
@@ -290,6 +299,40 @@ export function useGrowthStats() {
         .map(([method, count]) => ({ method, count }))
         .sort((a, b) => b.count - a.count);
 
+      // Robust volume — the figure worth trusting. It counts only MUTUAL trades
+      // (a listing attested by ≥2 distinct people, the signal a swap/ring would
+      // have to fake on BOTH sides), drops obviously-junk amounts, and caps how
+      // many trades any one pair can contribute (mirrors the reputation cap).
+      const MAX_TRADE_SATS = 100_000_000; // 1 BTC — above this the amount is junk
+      const PER_PAIR_CAP = 3;
+      const byListing = new Map<string, typeof trades>();
+      for (const t of trades) {
+        const coord = t.tags.find((x) => x[0] === 'a')?.[1];
+        if (!coord) continue;
+        const list = byListing.get(coord) ?? [];
+        list.push(t);
+        byListing.set(coord, list);
+      }
+      const pairCounts = new Map<string, number>();
+      const traders = new Set<string>();
+      let tradedSats = 0;
+      let tradedCount = 0;
+      for (const [, list] of byListing) {
+        const authors = [...new Set(list.map((e) => e.pubkey))];
+        if (authors.length < 2) continue; // one-sided = a claim, not a mutual trade
+        const amounts = list
+          .map((e) => Number(e.tags.find((x) => x[0] === 'amount')?.[1] ?? 0))
+          .filter((n) => Number.isFinite(n) && n > 0 && n <= MAX_TRADE_SATS);
+        const pairKey = [...authors].sort().join(':');
+        const used = pairCounts.get(pairKey) ?? 0;
+        if (used >= PER_PAIR_CAP) continue;
+        pairCounts.set(pairKey, used + 1);
+        tradedCount += 1;
+        tradedSats += amounts.length ? amounts[0] : 0;
+        for (const p of authors) traders.add(p);
+      }
+      const tradedTraders = traders.size;
+
       // ── Regions ──────────────────────────────────────────────────────────
       // Spots AND shops are considered together. A location's region comes from
       // its own `city`/`country` tag when present; otherwise it is DERIVED from
@@ -512,6 +555,9 @@ export function useGrowthStats() {
         totalListings: listings.length,
         totalTrades: trades.length,
         tradedSats,
+        tradedSatsClaimed,
+        tradedCount,
+        tradedTraders,
         tradesByMethod,
         zapCount,
         zapSats,

src/lib/queryPersister.ts

@@ -40,7 +40,7 @@ import type { Query } from '@tanstack/react-query';
 const IDB_KEY = 'skatespots:react-query-cache';
 
 /** Bump when the persisted data shape changes to invalidate old caches. */
-export const PERSIST_BUSTER = 'v4';
+export const PERSIST_BUSTER = 'v5';
 
 /** Discard any persisted cache older than this (ms). */
 export const PERSIST_MAX_AGE = 24 * 60 * 60 * 1000; // 24h

src/pages/CommunityStatsPage.tsx

@@ -361,8 +361,14 @@ export default function CommunityStatsPage() {
             </div>
           )}
           <p className="mt-3 text-[11px] leading-relaxed text-gray-600">
-            Sats traded are self-reported in trade records (the app can't observe an off-app payment).
-            "Zaps to mappers" counts only receipts addressed to our top contributors — it is
+            <strong className="text-gray-400">{stats?.tradedCount ?? 0}</strong> mutual trade
+            {(stats?.tradedCount ?? 0) === 1 ? '' : 's'} across{' '}
+            <strong className="text-gray-400">{stats?.tradedTraders ?? 0}</strong> people. Sats are
+            self-reported by the traders — the app can't observe an off-app payment — so the headline
+            counts only <strong className="text-gray-400">mutual</strong> trades with a per-pair cap;
+            the raw claim is{' '}
+            <strong className="text-gray-500">{(stats?.tradedSatsClaimed ?? 0).toLocaleString()}</strong>{' '}
+            sats. "Zaps to mappers" counts only receipts addressed to our top contributors — it is
             <strong className="text-gray-500"> not </strong> global zap volume.
           </p>
         </section>